Hot sheet metal forming by gas and direct quenching

ABSTRACT

A hot forming by gas and direct quenching method and apparatus are disclosed. One method of using the system includes a heating step, a forming step, and a direct quenching step. This method increases the quenching speed and allows common steels with high critical cooling rate to be hot formed and quenched. This method reduces or eliminates the need for a furnace and/or the coating of the workpiece prior to the forming, as well as the removal of the coating after the forming. Furthermore, by using a hot gas containing carbon or nitrogen, the workpiece may be case hardened after the heating, forming and quenching steps.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to an Iran ApplicationSerial Number 139550140003006618 filed on Aug. 23, 2016, which isincorporated by reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a method and apparatus forforming a metal plate. More specifically, the present applicationrelates to a method and apparatus for hot forming with a hot gas anddirect quenching a metal plate.

BACKGROUND

Weight reduction and improvement of crash safety in automotive andtransportation industries are of special importance, as these featureslead to lower fuel consumption and environmental emissions. To meetthese requirements, the use of a hot stamping process for the productionof ultra-high strength components in the automotive industry has beensteadily increasing. In conventional hot stamping methods, stamped partsare held at the bottom ‘dead center’ of a press for about ten secondsfor cooling. In these cases, the productivity is relatively low. Inaddition, a special type of steel that includes boron is necessary tolower the critical cooling rate.

SUMMARY

This summary is intended to provide an overview of the subject matter ofthe present disclosure, and is not intended to identify essentialelements or key elements of the subject matter, nor is it intended to beused to determine the scope of the claimed implementations. The properscope of the present disclosure may be ascertained from the claims setforth below in view of the detailed description below and the drawings.

In one general aspect, the present disclosure describes a hot sheetmetal forming with gas and direct quenching system. In oneimplementation, the system includes a gas chamber, a workpiece disposedabove the gas chamber, a die disposed above the workpiece, where the dieincludes a die cavity. The system also includes a hot gas, where the hotgas enters the die cavity through a die inlet and exits the die cavitythrough a die outlet, and where the hot gas enters the gas chamberthrough a gas chamber inlet and exits the gas chamber through a gaschamber outlet. Furthermore, the system has a plurality of nozzlesdisposed within the gas chamber, where a fluid or mist can be injectedinto the gas chamber through the plurality of nozzles.

The above general aspect may include one or more of the followingfeatures. In one example, the fluid or mist includes a mixture of waterand dissolved air. In addition, in some cases, the workpiece can includea steel sheet or a composite of plain-carbon steel and low-carbon steel.In some implementations, the hot gas contains carbon and/or nitrogen. Inanother example, the workpiece includes a material selected from thegroup consisting of aluminum alloys, titanium alloys, and magnesiumalloys. Furthermore, the workpiece may be configured to be movedmanually or automatically in order to change or adjust a distancebetween the workpiece and the die, such that the system includes anadjustment mechanism to readily control or change the distance betweenthe workpiece and the die. In one case, the nozzles are spaced apartfrom one another.

In another general aspect, the present disclosure describes a hot sheetmetal forming and direct quenching method. The method includes a heatingstep, a forming step, and a quenching step. In some implementations, theheating step includes positioning a workpiece between a die and gaschamber, moving a heated gas into a die cavity disposed above theworkpiece via a die inlet and out of the die cavity via a die outlet,moving the heated gas into the gas chamber below the workpiece via a gaschamber inlet and out of the gas chamber via a gas chamber outlet, andheating the workpiece by application of the injected heated gas. Inaddition, the forming step can include circulating the heated gas insidethe die cavity via the die inlet and the die outlet, circulating theheated gas inside the gas chamber below the workpiece via the gaschamber inlet and the gas chamber outlet, and forming the workpiece byincreasing the gas pressure in the gas chamber and forming the workpieceto the die, the die being disposed above the workpiece. The quenchingstep can involve closing the die inlet and the gas chamber inlet,opening the second outlet, and de-pressurizing the gas chamber byreleasing the heated gas from below the workpiece, opening a pluralityof nozzles and injecting a high-pressure cold fluid or mist, and coolingthe workpiece by application of the high-pressure cold fluid or mist.

The above general aspect may include one or more of the followingfeatures. In one example, the heating step occurs in a furnace that isseparate from the gas chamber. In addition, in some cases, the coldfluid or mist is a mixture of water and dissolved air. In otherimplementations, the workpiece includes a steel sheet, or a composite ofplain-carbon steel and low-carbon steel. In some cases the hot gasincludes carbon and/or nitrogen. In other implementations the workpieceis selected from the group consisting of aluminum alloys, titaniumalloys, and magnesium alloys. In one example, the heated gas includescarbon, while in other cases the heated gas includes nitrogen, or bothcarbon and nitrogen.

Other systems, methods, features and advantages of the implementationswill be, or will become, apparent to one of ordinary skill in the artupon examination of the following figures and detailed description. Itis intended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the implementations, and be protected by the claims

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accord withthe present teachings, by way of example only, not by way of limitation.In the figures, like reference numerals refer to the same or similarelements.

FIGS. 1A-1D depict a series of flow charts illustrating implementationsof a method of using the disclosed forming and quenching system; and

FIG. 2 illustrates one implementation of a hot gas forming and quenchingsystem.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant teachings. However, it should be apparent that the presentteachings may be practiced without such details. In other instances,well known methods, procedures, components, and/or circuitry have beendescribed at a relatively high-level, without detail, in order to avoidunnecessarily obscuring aspects of the present teachings. The followingdetailed description is presented to enable a person skilled in the artto make and use the methods and devices disclosed in exemplaryembodiments of the present disclosure. For purposes of explanation,specific nomenclature is set forth to provide a thorough understandingof the present disclosure. However, it will be apparent to one skilledin the art that these specific details are not required to practice thedisclosed exemplary embodiments. Descriptions of specific exemplaryembodiments are provided only as representative examples. Variousmodifications to the exemplary implementations will be readily apparentto one skilled in the art, and the general principles defined herein maybe applied to other implementations and applications without departingfrom the scope of the present disclosure. The present disclosure is notintended to be limited to the implementations shown, but is to beaccorded the widest possible scope consistent with the principles andfeatures disclosed herein.

Stamping refers to the forming of a workpiece (such as a sheet metal orblank) into a desired shape. During hot stamping, heating of the desiredworkpiece is generally performed in a furnace after which the workpieceis placed in a forming machine. Thus, one hot stamping process caninclude a series of independent operations such as heating, handling,and forming of the workpiece.

The present disclosure describes a hot sheet metal forming and directquenching system. In different implementations, the hot sheet metalforming utilizes a gas. For purposes of reference, FIGS. 1A-1D provide aseries of flow charts illustrating implementations of a method of usingthe disclosed hot sheet metal forming and direct quenching system.

As a general overview, it can be understood that in someimplementations, the system includes a workpiece, a gas chamber, a die,a die inlet, a gas chamber inlet, a die outlet, a chamber outlet, one ormore fluids (such as a gas, liquid, or mixture of them), and a pluralityof nozzles. Furthermore, the heating step can be implemented bydifferent methods, such as induction heating, resistive heating,industrial furnaces, and other such methods. In one aspect of thepresent application, the heating step includes heating by a hot gas. Inthis method, a hot gas with low pressure is injected into the gaschamber and die cavity to heat both sides of the workpiece. The hot gasenters the die cavity through a die inlet and exits from the die outletabove the workpiece. The hot gas also enters the gas chamber through achamber inlet and exits from the chamber outlet below the workpiece.Although this method can be slower than other heating methods, it canreduce or eliminates the necessity of using a furnace, the step ofcoating the workpiece prior to the forming, and the step of removing thecoating after the forming. Furthermore, by using a hot gas containingcarbon or nitrogen, the workpiece (made of plain-carbon steel andlow-carbon steel) may be case hardened after the forming and quenchingsteps.

In addition, the forming step can include an application of force ofhigh pressure hot gas. The high pressure hot gas enters the gas chamberthrough the chamber inlet below the workpiece and pushes the workpieceinto the die in a substantially continuous manner. As a result, theworkpiece forms into the shape of the die. The low pressure hot gas maybe injected into the space between the workpiece and the die via the dieinlet to help maintain the temperature of the die at a substantiallyconstant temperature. It should be noted that in some implementationsthe temperature of the workpiece is also maintained around asubstantially constant temperature during the forming step by flowing ofhigh pressure hot gas.

During the quenching step, the die and chamber inlets are closed and thedie and chamber outlets are opened to permit the high pressure hot gasto at least partially exit. Afterwards, the high-pressure cold fluid ormist enters the gas chamber through a plurality of nozzles. Theplurality of nozzles can be located or extend from the pressure chamberin some implementations. In one implementation, each nozzle is arrangedat a distance from a neighboring nozzle (spaced apart) relative to oneanother. In some implementations, the nozzles are arranged such thatthey extend along a wall or surface of the gas chamber in a mannercorresponding to the substantial entirety of the length of theworkpiece.

In one implementation, the high-pressure cold fluid or mist can comprisea mixture of water and dissolved air. The turbulent flow regime of thehigh-pressure cold fluid or mist causes rapid quenching of theworkpiece.

It should be noted that the heating step may be done in a separateprocess and in a furnace, where the furnace is separate from the gaschamber. In these cases, the workpiece should be coated before theheating by an insulator layer to avoid oxidation during heating process.The workpiece may be moved between the furnace and the gas chambermanually or automatically.

In another aspect of the present application, the method and the systempresented may be used to form metal sheets other than iron and steel,such as aluminum alloys, titanium alloys, magnesium alloys, etc.

Referring now to FIGS. 1A-1D, for purposes of clarity an overview of animplementation of the method. As shown in FIG. 1A, one implementation ofa method of forming a sheet metal using this system generally comprisesthree steps. In a first step 110, the workpiece is heated. In a secondstep 112, the workpiece is formed by the system, and in a third step114, direct quenching of the workpiece occurs. Additional details withrespect to each of these steps are provided further below.

Referring now to FIG. 1B, an implementation of a heating step for aworkpiece is illustrated in a flow chart. A first step 120 comprisespositioning a workpiece between a die and gas chamber. A second step 122includes moving a heated gas into the die cavity above the workpiece viaa die inlet and a die outlet. In some implementations, the die inlet canbe located above or below the workpiece along a first end of the diecavity, and the die outlet can be located above or below the workpieceand along a second end of the die chamber. In a third step 124, a heatedgas is moved into the gas chamber below the workpiece via a gas chamberinlet and a gas chamber outlet. In some implementations, the gas chamberinlet is located below the workpiece and along the first end of the gaschamber, and the gas chamber outlet is located below the workpiece andalong the second end of the gas chamber. A fourth step 126 comprisesheating the workpiece by controlling a temperature of the injectedheated gases for a duration that the injected heated gases are incontact with the workpiece.

As shown in FIG. 1C, an implementation of a method of forming theworkpiece is illustrated in a flow chart. A first step 130 involvescirculating the heated gas inside the die cavity via the die inlet andthe die outlet. In a second step 132, the heated gas is also circulatedinside the gas chamber below the workpiece via the gas chamber inlet andthe gas chamber outlet. A third step 134 comprises forming the workpieceby increasing the gas pressure inside the gas chamber and forming theworkpiece to the die.

An implementation of a method of quenching is illustrated in a flowchart in FIG. 1D. A first step 140 includes closing the die inlet andthe gas chamber inlet. In some implementations the closure of thesecomponents can occur very close in time, or in a substantiallysimultaneous manner. A second step 142 includes opening the secondoutlet and de-pressurizing the gas chamber by exiting the heated gasfrom below the workpiece. A third step 144 comprises opening a pluralityof nozzles and injecting a high-pressure cold fluid or mist. In a fourthstep 146, the workpiece is cooled down by a flowing or application ofthe high-pressure cold fluid or mist. Further details regarding thesesteps are disclosed further with respect to the description of theapparatus in FIG. 2 below.

Referring now to FIG. 2, for purposes of clarity, one implementation ofa hot stamping and quenching system (“system”) 200 is depicted. In FIG.2, the system 200 includes a workpiece 216, a gas chamber 220, a die222, a die inlet 224, a gas chamber inlet 226, a die outlet 228, a gaschamber outlet 230, a hot gas 232, and a plurality of nozzles 234. Inone implementation, the die can be disposed or positioned at anadjustable distance from the workpiece, or can be pressed into varyingdistances from the workpiece.

In different implementations, the heating step (as introduced in FIGS.1A and 1B above) may utilize different methods, such as inductionmethods, resistive methods, industrial furnaces, and other heatingmethods. In one implementation of the present application, the heatingstep may include heating by application of a hot or heated gas. In oneimplementation of this method, a hot gas 232 with relatively lowpressure is injected into the gas chamber 220 and die cavity 222, whichapplies heat to both sides of the workpiece 216. The hot gas 232 canenter the die cavity 222 and gas chamber 220 through one or more inlets.For example, in FIG. 2, the hot gas 232 enters the die cavity 222through die inlet 224 disposed above the workpiece 216 and enters thegas chamber 220 through a gas chamber inlet 226 disposed below theworkpiece 216. Although in some cases this method can be slower thansome other types of heating methods, it provides the benefit of reducingor eliminating the requirement of using a furnace. Furthermore, in thepresent method, a coating of the workpiece prior to the forming may notbe necessary, nor the step of removing the coating after the forming. Inaddition, by using a hot gas 232 that comprises carbon and/or nitrogen,the workpiece 216 made of plain-carbon steel and low-carbon steel mayalso be case hardened after the heating, forming and quenching step.

Following the heating of the workpiece, there follows a forming step (asintroduced in FIGS. 1A and 1C above). In some implementations, theforming step may include the use of a forming force associated with thehigh pressure hot gas 232. The high pressure hot gas 232 enters throughthe gas chamber inlet 226 below the workpiece 216 and can act to pushthe workpiece 216 into the die 222 in a substantially continuous manner.As a result, the workpiece 216 begins to form into a shape associatedwith the die 222. Low pressure hot gas 232 may also be injected into thespace between the workpiece 216 and the die 222 via the die inlet 224,and help to keep the temperature of the die 222 substantially constant.Thus, in one implementation, the workpiece 216 is maintained at asubstantially constant temperature during the forming step 212 bycontrolling the temperature of the high pressure hot gas 232.

With respect to the quenching step (introduced in FIGS. 1A and 1Dabove), in some cases, the die inlet 224 and the gas chamber inlet 226may close and the second outlet 230 may open to permit the high pressurehot gas 232 to at least partially exit the chamber. Afterwards,high-pressure cold fluid or mist is injected in or is in communicationwith the gas chamber 220 through a plurality of nozzles 234. In oneimplementation, the cold fluid or mist can comprise a mixture of waterand dissolved air. The turbulent flow regime of the high-pressure coldfluid or mist causes rapid quenching of the workpiece 216.

Furthermore, in different implementations, the heating step disclosedherein can occur as a separate process. For example, the heating stepcan occur in a furnace, where the furnace is separate from the gaschamber. The workpiece may be moved between the furnace and the gaschamber manually or automatically.

In another aspect of the present application, the method and the systempresented may be used to form metal sheets other than iron and steel(for example, aluminum alloys, titanium alloys, magnesium alloys, andother such metals).

While the foregoing has described what are considered to be the bestmode and/or other examples, it is understood that various modificationsmay be made therein and that the subject matter disclosed herein may beimplemented in various forms and examples, and that the teachings may beapplied in numerous applications, only some of which have been describedherein. It is intended by the following claims to claim any and allapplications, modifications and variations that fall within the truescope of the present teachings.

Unless otherwise stated, all measurements, values, ratings, positions,magnitudes, sizes, and other specifications that are set forth in thisspecification, including in the claims that follow, are approximate, notexact. They are intended to have a reasonable range that is consistentwith the functions to which they relate and with what is customary inthe art to which they pertain.

The scope of protection is limited solely by the claims that now follow.That scope is intended and should be interpreted to be as broad as isconsistent with the ordinary meaning of the language that is used in theclaims when interpreted in light of this specification and theprosecution history that follows and to encompass all structural andfunctional equivalents. Notwithstanding, none of the claims are intendedto embrace subject matter that fails to satisfy the requirement ofSections 101, 102, or 103 of the Patent Act, nor should they beinterpreted in such a way. Any unintended embracement of such subjectmatter is hereby disclaimed.

Except as stated immediately above, nothing that has been stated orillustrated is intended or should be interpreted to cause a dedicationof any component, step, feature, object, benefit, advantage, orequivalent to the public, regardless of whether it is or is not recitedin the claims.

It will be understood that the terms and expressions used herein havethe ordinary meaning as is accorded to such terms and expressions withrespect to their corresponding respective areas of inquiry and studyexcept where specific meanings have otherwise been set forth herein.Relational terms such as first and second and the like may be usedsolely to distinguish one entity or action from another withoutnecessarily requiring or implying any actual such relationship or orderbetween such entities or actions. The terms “comprises,” “comprising,”or any other variation thereof, are intended to cover a non-exclusiveinclusion, such that a process, method, article, or apparatus thatcomprises a list of elements does not include only those elements butmay include other elements not expressly listed or inherent to suchprocess, method, article, or apparatus. An element proceeded by “a” or“an” does not, without further constraints, preclude the existence ofadditional identical elements in the process, method, article, orapparatus that comprises the element.

The Abstract of the Disclosure is provided to allow the reader toquickly ascertain the nature of the technical disclosure. It issubmitted with the understanding that it will not be used to interpretor limit the scope or meaning of the claims. In addition, in theforegoing Detailed Description, it can be seen that various features aregrouped together in various implementations. This is for purposes ofstreamlining the disclosure, and is not to be interpreted as reflectingan intention that the claimed implementations require more features thanare expressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed implementation. Thus, the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separately claimed subject matter.

While various implementations have been described, the description isintended to be exemplary, rather than limiting and it will be apparentto those of ordinary skill in the art that many more implementations andimplementations are possible that are within the scope of theimplementations. Although many possible combinations of features areshown in the accompanying figures and discussed in this detaileddescription, many other combinations of the disclosed features arepossible. Any feature of any implementation may be used in combinationwith or substituted for any other feature or element in any otherimplementation unless specifically restricted. Therefore, it will beunderstood that any of the features shown and/or discussed in thepresent disclosure may be implemented together in any suitablecombination. Accordingly, the implementations are not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A hot sheet metal forming and direct quenchingsystem for forming a workpiece, the system comprising: a gas chamber; aworkpiece disposed above the gas chamber; a die disposed above theworkpiece, the die including a die cavity; a hot gas, wherein the hotgas enters the die cavity through a die inlet and exits the die cavitythrough a die outlet, and wherein the hot gas enters the gas chamberthrough a gas chamber inlet and exits the gas chamber through a gaschamber outlet; a plurality of nozzles disposed within the gas chamber;and a fluid or mist being injected into the gas chamber through theplurality of nozzles.
 2. The system of claim 1, wherein the fluid ormist includes a mixture of water and dissolved air.
 3. The system ofclaim 1, wherein the workpiece includes a steel sheet.
 4. The system ofclaim 1, wherein the workpiece includes a composite of plain-carbonsteel and low-carbon steel.
 5. The system of claim 4, wherein the hotgas contains carbon and/or nitrogen.
 6. The system of claim 1, whereinthe workpiece includes a material selected from the group consisting ofaluminum alloys, titanium alloys, and magnesium alloys.
 7. The system ofclaim 1, wherein the workpiece is configured to be moved manually orautomatically in order to change a distance between the workpiece andthe die.
 8. The system of claim 1, wherein the nozzles are spaced apartfrom one another.
 9. A hot sheet metal forming and direct quenchingmethod, the method comprising: a heating step, the heating stepcomprising: positioning a workpiece between a die and gas chamber;moving a heated gas into a die cavity disposed above the workpiece via adie inlet and out of the die cavity via a die outlet; moving the heatedgas into the gas chamber below the workpiece via a gas chamber inlet andout of the gas chamber via a gas chamber outlet; and heating theworkpiece by application of the injected heated, gas; a forming stepcomprising: circulating the heated gas inside the die cavity via the dieinlet and the die outlet; circulating the heated gas inside the gaschamber below the workpiece via the gas chamber inlet and the gaschamber outlet; forming the workpiece by increasing the gas pressure inthe gas chamber and forming the workpiece to the die, the die beingdisposed above the workpiece; a quenching step comprising: closing thedie inlet and the gas chamber inlet; opening the second outlet andde-pressurizing the gas chamber by releasing the heated gas from belowthe workpiece; opening a plurality of nozzles and injecting ahigh-pressure cold fluid or mist; and cooling the workpiece byapplication of the high-pressure cold fluid or mist.
 10. The method ofclaim 9, wherein the heating step occurs in a furnace that is separatefrom the gas chamber.
 11. The method of claim 9, wherein the cold fluidor mist is a mixture of water and dissolved air.
 12. The method of claim9, wherein the workpiece includes a steel sheet.
 13. The system of claim9, wherein the workpiece includes a composite of plain-carbon steel andlow-carbon steel.
 14. The system of claim 9, wherein the gas includescarbon and/or nitrogen
 15. The method of claim 9, wherein the workpieceis selected from the group consisting of aluminum alloys, titaniumalloys, and magnesium alloys.
 16. The method of claim 9, wherein theheated gas includes carbon.
 17. The method of claim 9, wherein theheated gas includes nitrogen.